Forbidden error....page does not exist

hi guys am kinda worried, i've got a Linux box( Red Hat 2.6.9-5.Elsmp), am trying to configure as a web server, it came pre installed with apache,mysql and Php, after starting the web server (httpd start), then i saw the default page showing i can add my html files to /var/www/html directory,upon adding the files to the directory and opening it in (http://localhost/sample.php)... i received an error saying the file sample.php does not exist ......
what am i gonna do?.....

Check the permissions on the sample.php file. running out of /var/www/
html, chances are it needs to be owned and readable by the apache
process - most likely user : nobody
If the file is owned by root with permissions like -rwx------ then
'nobody' cannot read the file.

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